feat: Initial release v0.1.0

STP/STEP 3D viewer (WPF, .NET 8) - CADability + HelixToolkit.Wpf:

- Multi-file import (STEP/STL/DXF) with STEP assembly tree
  (per-node visibility/color cascade, zoom-to)
- Measurements: point / distance / edge / face / circle / angle /
  face-to-face distance (B-rep exact where available)
- Assembly verification: two-point align (translate), 3-point align
  (rotate+translate via RigidAlign), axis rotate 90, interference
  check (tri-tri intersection + min gap)
- Section view (CPU mesh clipping, originals preserved)
- mm/inch toggle, CSV export (UTF-8 BOM), 2x PNG screenshot
- Performance: per-file merged edge lines, per-leaf merged mesh in
  browse mode, no BackMaterial on closed solids, edge suspend during
  camera interaction, parallel leaf triangulation with retry
- SmokeTest CLI: import pipeline, --tree, --clip-test,
  --interference-test, --align-test (all passing)

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

tools/SmokeTest/MakeDxf.cs

@@ -0,0 +1,17 @@
+// 測試輔助：用 CADability 內嵌的 netDxf 產生標準 DXF 測試檔
+using netDxf;
+using netDxf.Entities;
+
+namespace SmokeTest;
+
+internal static class MakeDxf
+{
+    public static void Run(string path)
+    {
+        var doc = new DxfDocument();
+        doc.Entities.Add(new Line(new Vector3(0, 0, 0), new Vector3(100, 50, 0)));
+        doc.Entities.Add(new Circle(new Vector3(50, 25, 0), 10));
+        doc.Save(path);
+        Console.WriteLine($"已產生 {path}");
+    }
+}